Method of preparing mats for use in making printing plates



Patented Sept. 3, 1929.

UNITED STATES PATENT OFFICE.

EARLE E. MARTIN,- OF CLEVELAND, OHIO.

METHOD OF PREPARING MATS FOR NoDrawing.

This invention relates to the manufacture of stereotype plates and more particularly to the preparation of the mats that are used therein.

The dry matrix process, now in common use in newspaper stereotype departments, has not been entirely satisfactory because of the inability to produce stereotype plates of uniform size. It is important, in running an 10 edition of a newspaper, to have the plates of uniform size because lack of uniformity results in a material loss of paper. hen the plates vary in size the sheet of paper must be large enough to accommodate the largest plate and still leave the desired margin. It is apparent, therefore, that if the plates of an edition of a newspaper were of uniform size and that size was the minimum now used, then the size of the printed sheet could be gauged to this minimum, whereas it is now necessary to gauge the size of the sheet to the largest plate.

The variation in the size of the stereotype plates is due to a variation in the amount of moisture in the mats. The mats are made of papier-mach and swell when moistened and shrink when dried. The mats are moistened before being subjected to the pressure of the type-form, for the purpose of making the matrix. It is, therefore, important to have the mats uniformly moistened so that, when dried, they will shrink to a uniform size.

It is the object of the present invention to provide a method of moi-sterling the mats that will insure uniformity in results and permit the production of stereotype plates of uniform size so as to avoid the paper loss that is now incidental to the manufacture of newspapers because of the lack of uniformity in the size of the plates. A further object is to provide a better quality of printing plates.

In practicing my invention I arrange the mats, face-to-face, in pairs, and stack these pairs with moistened pads between the backs of the mats. These pads preferably consist of heavy linen cloth which has been folded once to give two thicknesses. Prior to their arrangement in the stack the pads are saturated with Water and then run lightly through a wringer to insure uniform dampness. Each stack should comprise a sufficient number of pairs of pads to produce the plates of a complete edition of the newspaper or other matter to be printed and when a stack has been formed a metal plate is placed on top of the Application filed July 25,

USE IN MAKING PRINTING PLATES? 1928. Serial No. 295,356.

stack for the purpose of exerting sutlicient pressure thereon to prevent any buckling of the mats and to keep thelinen and mats in intimate contact.

The stack, with the metal plate thereon, is then placed in a closed chamber of sufficient size to permit air to freely circulate around all sides of the stack. This should preferably be a refrigeration chamber and any preferred method of refrigeration may be used but it is important that the tempertureof the chamber be maintained substantially uniform during the period that the mats remain therein. I have found that the temperature should be 50 or less but above freezing and it is preferable to have each stack of mats in a separate chamber and there should also be arranged in this chamber a pan of water or other means for supplying suflicient moisture to the chamber to keep the atmosphere therein in a substantially saturated condition.

The stack of mats will be, under the procedure above set forth, moistened in a thoroughly uniform manner, throughout, by the fourth day after being put into the chamber and are then ready for use. It is extremely important to maintain this uniformity of dampness in the mats until the moment of their use and, in order to accomplish this, 8

I recommend that the stack, when removed from the chamber, be placed in a closed metal box in which it may be transferred to the point where it is to be used. The mats may then be removed from the box, one at a time, and used in the matrix-rolling machine.

Having thus described my invention, what I claim is:

1. The hereindescribed method of preparing mats for use in making printing plates, which consists in stacking a plurality of pairs of mats with the mats of each pair face-toface, and with moisture-containing pads between the respective pairs and then maintaining the stack in a substantially saturated atmosphere in a closed chamber at a constant temperature for a sufficient period of time to enable the mats to become uniformly moistened throughout.

2. The hereindescribed method of preparing mats for use in making printing plates, which consists in stacking a plurality of pairs of mats with the mats of each pair face-toface, and with moisture-containing pads between the respective pairs, subjecting the pads between the respective pairs subjecting the stack to a suflicient pressure to insure uniform contact between the mats and pads and to prevent the mats from buckling, and then maintaining the stack in a substantially saturated atmosphere and at a substantially uniform temperature of about 50 F. in a closed chamber for a sufficient period of time to enable the mats to become uniformly moistened throughout.

In testimony whereof, I hereunto ai fix my signature.

EARLE E. MARTIN. 

